scholarly journals Light Affects the Branching Pattern of Peptidergic Circadian Pacemaker Neurons in the Brain of the Cockroach Leucophaea maderae

2011 ◽  
Vol 26 (6) ◽  
pp. 507-517 ◽  
Author(s):  
Hongying Wei ◽  
Monika Stengl
Keyword(s):  
Fruit Flies ◽  
Branching Pattern ◽  
Circadian Pacemaker ◽  
Pacemaker Neurons ◽  
Optic Lobes ◽  
Pigment Dispersing Factor ◽  
Accessory Medulla ◽  
Leucophaea Maderae ◽  
The Brain

Pigment-dispersing factor–immunoreactive neurons anterior to the accessory medulla (aPDFMes) in the optic lobes of insects are circadian pacemaker neurons in cockroaches and fruit flies. The authors examined whether any of the aPDFMes of the cockroach Leucophaea maderae are sensitive to changes in period and photoperiod of light/dark (LD) cycles as a prerequisite to adapt to changes in external rhythms. Cockroaches were raised in LD cycles of 11:11, 13:13, 12:12, 6:18, or 18:6 h, and the brains of the adults were examined with immunocytochemistry employing antisera against PDF and orcokinin. Indeed, in 11:11 LD cycles, only the number of medium-sized aPDFMes specifically decreased, while it increased in 13:13. In addition, 18:6 LD cycles increased the number of large- and medium-sized aPDFMes, as well as the posterior pPDFMes, while 6:18 LD cycles only decreased the number of medium-sized aPDFMes. Furthermore, PDF-immunoreactive fibers in the anterior optic commissure and orcokinin-immunoreactive fibers in both the anterior and posterior optic commissures were affected by different lengths of light cycles. Thus, apparently different groups of the PDFMes, most of all the medium-sized aPDFMes, which colocalize orcokinin, respond to changes in period and photoperiod and could possibly allow for the adjustment to different photoperiods.

Myoinhibitory peptides in the brain of the cockroach Leucophaea maderae and colocalization with pigment-dispersing factor in circadian pacemaker cells

2012 ◽  
Vol 520 (5) ◽  
pp. 1078-1097 ◽  
Author(s):  
Julia Schulze ◽  
Susanne Neupert ◽  
Lilia Schmidt ◽  
Reinhard Predel ◽  
Tobias Lamkemeyer ◽  
...  
Keyword(s):  
Circadian Pacemaker ◽  
Pacemaker Cells ◽  
Pigment Dispersing Factor ◽  
Leucophaea Maderae ◽  
The Brain

Gap Junctions Between Accessory Medulla Neurons Appear to Synchronize Circadian Clock Cells of the Cockroach Leucophaea maderae

2006 ◽  
Vol 95 (3) ◽  
pp. 1996-2002 ◽  
Author(s):  
Nils-Lasse Schneider ◽  
Monika Stengl
Keyword(s):  
Gap Junctions ◽  
Circadian Clock ◽  
Phase Difference ◽  
Temporal Organization ◽  
Stable Phase ◽  
Circadian Pacemaker ◽  
Potential Oscillations ◽  
Synaptic Release ◽  
Accessory Medulla ◽  
Leucophaea Maderae

The temporal organization of physiological and behavioral states is controlled by circadian clocks in apparently all eukaryotic organisms. In the cockroach Leucophaea maderae lesion and transplantation studies located the circadian pacemaker in the accessory medulla (AMe). The AMe is densely innervated by γ-aminobutyric acid (GABA)–immunoreactive and peptidergic neurons, among them the pigment-dispersing factor immunoreactive circadian pacemaker candidates. The large majority of cells of the cockroach AMe spike regularly and synchronously in the gamma frequency range of 25–70 Hz as a result of synaptic and nonsynaptic coupling. Although GABAergic coupling forms assemblies of phase-locked cells, in the absence of synaptic release the cells remain synchronized but fire now at a stable phase difference. To determine whether these coupling mechanisms of AMe neurons, which are independent of synaptic release, are based on electrical synapses between the circadian pacemaker cells the gap-junction blockers halothane, octanol, and carbenoxolone were used in the presence and absence of synaptic transmission. Here, we show that different populations of AMe neurons appear to be coupled by gap junctions to maintain synchrony at a stable phase difference. This synchronization by gap junctions is a prerequisite to phase-locked assembly formation by synaptic interactions and to synchronous gamma-type action potential oscillations within the circadian clock.

Evidence for a role of GABA and Mas-allatotropin in photic entrainment of the circadian clock of the cockroach Leucophaea maderae

2002 ◽  
Vol 205 (10) ◽  
pp. 1459-1469 ◽  
Author(s):  
Bernhard Petri ◽  
Uwe Homberg ◽  
Rudolf Loesel ◽  
Monika Stengl
Keyword(s):  
Fruit Fly ◽  
Phase Response ◽  
Stable Phase ◽  
Circadian Pacemaker ◽  
Response Curves ◽  
Phase Response Curves ◽  
Accessory Medulla ◽  
Leucophaea Maderae ◽  
Central Pacemaker

SUMMARY Accumulating evidence suggests that the accessory medulla is the location of the circadian pacemaker in the fruit fly Drosophila melanogasterand the cockroach Leucophaea maderae. γ-Aminobutyric acid(GABA) and Mas-allatotropin are two putative neurotransmitters, in the accessory medulla in the cockroach Leucophaea maderae. Neurons immunoreactive to the neuropeptide Mas-allatotropin are local neurons with arborizations in the noduli of the accessory medulla, while GABA-immunoreactive neurons connect the noduli of the accessory medulla to the medulla and to the lamina via processes in the distal tract. Injections of GABA and Mas-allatotropin into the vicinity of the accessory medulla resulted in stable phase-dependent resetting of the circadian locomotor activity of the cockroach. The resulting phase response curves closely matched light-dependent phase response curves, suggesting that both substances play a role in circuits relaying photic information from circadian photoreceptors to the central pacemaker.

scholarly journals Differential regulation of the Drosophila sleep homeostat by circadian and arousal inputs

eLife ◽  
2019 ◽  
Vol 8 ◽  
Author(s):  
Jinfei D Ni ◽  
Adishthi S Gurav ◽  
Weiwei Liu ◽  
Tyler H Ogunmowo ◽  
Hannah Hackbart ◽  
...  
Keyword(s):  
Circadian Clock ◽  
Differential Regulation ◽  
Central Complex ◽  
Synaptic Connections ◽  
Circadian Pacemaker ◽  
Pacemaker Neurons ◽  
Synaptic Inputs ◽  
Shaped Body ◽  
Sleep Homeostat ◽  
The Brain

One output arm of the sleep homeostat in Drosophila appears to be a group of neurons with projections to the dorsal fan-shaped body (dFB neurons) of the central complex in the brain. However, neurons that regulate the sleep homeostat remain poorly understood. Using neurogenetic approaches combined with Ca2+ imaging, we characterized synaptic connections between dFB neurons and distinct sets of upstream sleep-regulatory neurons. One group of the sleep-promoting upstream neurons is a set of circadian pacemaker neurons that activates dFB neurons via direct glutaminergic excitatory synaptic connections. Opposing this population, a group of arousal-promoting neurons downregulates dFB axonal output with dopamine. Co-activating these two inputs leads to frequent shifts between sleep and wake states. We also show that dFB neurons release the neurotransmitter GABA and inhibit octopaminergic arousal neurons. We propose that dFB neurons integrate synaptic inputs from distinct sets of upstream sleep-promoting circadian clock neurons, and arousal neurons.

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